HAdV-41 stimulates serotonin release from human EC cells. (A) Dose-response release of serotonin. Purified HAdV-41 was diluted in MEM and incubated (150 μl) on EC cells for 24 h, followed by collection of cell medium and serotonin determination. (B) Purified HAdV-41 but not HAdV-5 (10 μg/ml, 150 μl) stimulates serotonin release from EC cells within 6 h. The diluent control was PBS. ***, P < 0.001, and *, P < 0.05, by Student's t test. Data are means ± SEM (n = 4).